Currently, in a long term evolution (LTE) radio communications network, deploying a wireless fidelity (Wi-Fi) network around a base station has become a mainstream trend of telecom operators. The Wi-Fi network has access features, such as free of charge and a high speed. Therefore, with ongoing increase of mobile Internet data service requirements, the Wi-Fi network will become a priority manner for a user to access the network.
The LTE network does not overlap the Wi-Fi network completely. The LTE can support high-speed data transmission properly to solve an access issue of a user in a high-speed movement scenario, while the Wi-Fi is suitable for low-speed user access and cannot support high-speed movement services. However, when a user keeps using a high-speed data service such as a video and an online game in the LTE network, due to limitation of channels and resources, it is easy to meet an extreme limit of a network capacity. In this case, the Wi-Fi network is integrated into the LTE network, and advantages of the Wi-Fi network will be reflected. Therefore, the Wi-Fi network is a strongest supporter of the LTE network. Both of them bring their respective advantages into full play, and collaborate with each other in high-speed access, low-speed and fixed access scenarios to provide better experience for users.
Generally, as shown in FIG. 1, when a user terminal is in a non-roaming state, a telecom operator integrates the Wi-Fi-LTE into a core network, and uses a packet data gateway of a home domain network to interact with a charging network element to perform charging. The packet data gateway obtains WLAN packet data of the user terminal from a wireless local area network (WLAN) access gateway, measures a traffic volume of the WLAN packet data of the user terminal, and performs charging by communicating with the charging network element mutually.
As shown in FIG. 2, when the user terminal is in a roaming state, the packet data gateway obtains the WLAN packet data of the user terminal from the WLAN access gateway, measures a traffic volume of the WLAN packet data of the user terminal, and uses an authentication-authorization-accounting (AAA) authentication proxy to transfer a user terminal identifier ID and traffic measurement information to the charging network element through an AAA authentication server of the home domain network, and the charging network element performs charging.
Therefore, the prior art integrates the Wi-Fi-LTE into the core network, which exposes the following defects: Throughout the charging, mutual communication is performed between the wireless local area network access gateway and each network element to ultimately implement the charging. Therefore, control signaling is distributed in each network element in the core network, which leads to a complicated communication process between network elements and increases management costs of the network; and many network elements participate in the communication, which leads to waste of device investment.